Field of the Invention
The present invention relates to the field of electrical systems. More particularly, the invention relates to electrical energy transmission systems which are used to transmit electrical energy generated by three-phase electric power sources over certain distances, including significantly long distances.
Background Art
An electrical energy transmission system for transmitting a generated three-phase current conventionally includes a three-phase electrical power generator and an electrical transmission line which transmits the generated electrical energy to a load.
There were attempts to carry out the electrical energy transmission by means of one wire. First applications of the single-wire electrical energy transmission were disclosed by Nikola Tesla in U.S. Pat. No. 1,119,736 and in British Patent No. 8,200. Another single line transmission technique is known as the Goubau line or G-line, which is a type of single wire transmission line used at UHF and microwave frequencies (see Geog Goubau, “Surface waves and their Application to Transmission Lines,” Journal of Applied Physics, Volume 21, November, 1950). However, a G-line is a type of waveguide, rather than a wire for an electric circuit. There was also an experiment based on the Russian patent application by Stanislav and Konstantin Avramenko [6-8}. All these concepts were based on signal processing, including frequency converting or signal straightening. They however negatively influence the process of transmission of electrical energy and lead to loss of power.
Also an electrical energy distribution method is known with the use of one conductor, however with a return of the electrical current through earth, according to the authors of the proposed method. This method is known as the Single Wire Earth Return (SWER). However, the simplification of the electrical energy transfer in this system is achieved due to the loss of a part of the power produced by the source due to the distance.
Three phase electrical energy transmission systems, in which conventionally electrical energy is transmitted by four wires has significant advantages. However, the presence of three or four wires is not the only drawback of the system. Another drawback is a line voltage between two wires in this system at the root of the three phase voltage. This may have negative consequences, such a corona effect and additional losses in the lines. Additional disadvantage of the three phase system is the need to arrange the wires at a distance of several meters from each other. This in turn makes difficult to use underground lines.
A further improvement to provide an electrical energy transmission system, which transmits electrical energy generated by a three-phase electrical power source is disclosed in U.S. patent application Ser. No. 14/555,951. An electrical energy transmission system disclosed in this patent application comprises a three-phase electric current power source or generator generating a three-phase electric current signal including three currents having different phases, a three-phase electric current signal converting device connected with said three-phase electric current source and converting the three-phase electric current signal generated by the latter, and a single-wire electrical energy transmission line connected with said converting device and transmitting further at least a part of the converted three-phase electric current signal. The electrical energy transmission system designed this way allows a transmission of at least a part of the three-phase electric current signal through the single-wire transmission line, which results in significant economy of wires, especially in the systems which carry out transmission of electrical energy generated by three-phase electrical power sources over significant distances.
It has been however determined that the electrical current transmission system constructed as specified hereinabove cause a disbalance of currents in the three-phase electric current generator, which negatively affect the operation of the three-phase electric current generator. Therefore is the electrical current transmission system must be further improved to prevent a stable operation of the three-phase electric current generator.